1. Field of the Invention
The present invention relates to a fuel tank opening-closing device, whereby insertion force of the fuel nozzle is utilized to open a shutter and permit filling of the fuel tank.
2. Description of the Related Art
One known technology of this kind, disclosed in WO 2005-077698A1, provides a shutter moveable in the diametrical direction of the fuel passage; an actuation ring adapted to be pushed by the fuel nozzle; and an interconnection mechanism for interlocked operation with the actuation ring to open the shutter. According to this design, the actuation ring is radially expanded by pushing the actuation ring with the tip of the fuel nozzle, and the displacement produced by this radial expansion is amplified by the interconnection mechanism, thereby producing opening movement of the shutter and making it possible to insert the fuel nozzle.
However, with the conventional system, the amount of displacement produced by radial expansion of the actuation ring does not exceed a few millimeters, and to open the shutter using this amount of displacement requires a high amplification ratio on the part of the interconnection mechanism. A resultant problem was that opening and closing movement of the shutter could be impeded due to frictional force occurring with even slight freezing up of the interconnection mechanism and/or shutter. An additional problem was that, in a preferred design whereby the pushed part of the actuation ring can be reliably pushed by the fuel nozzle and whereby the insertion force of the fuel nozzle can be utilized to actuate opening of the shutter, the pushed part of the actuation ring will be situated in an insertion passage only slightly larger than the circumference of the fuel nozzle, and the insertion passage will have a length such that the pushed part can be pushed along for a considerable distance; however, a long narrow insertion passage of such design results in poor ease of operation during fuel nozzle insertion.